China says the United States is trying to “stir up trouble” by dispatching military vessels to the vicinity of disputed islands in the South China Sea, which Beijing regards as sovereign Chinese territory.

On Monday, the guided-missile destroyer USS Spruance and USS Preble sailed within 12 nautical miles of Meiji Reef in the Nansha Archipelago, which is also known as Spratly Islands, in the South China Sea under what Washington calls “freedom of navigation operations,” Reuters reported, citing an unnamed American official.

A few hours later, Chinese Foreign Ministry spokeswoman Hua Chunying confirmed the news at a daily press briefing and said the US had violated China’s sovereignty by trespassing on its territorial waters, Presstv Reported.

Washington “is determined to stir up trouble in the South China Sea, create tension, and undermine peace,” she said, urging the US to cease the “provocative actions.”

China claims sovereignty over nearly all of the resource-rich South China Sea, through which five trillion dollars in shipping trade passes annually. There are competing claims to the islands from Brunei, Malaysia, the Philippines, Taiwan, and Vietnam.

The US has taken sides with China’s rival claimants in the territorial dispute, stepping up military presence under the pretext of “freedom of navigation operations” in “international” waters, which Beijing considers as provocation.

China has largely exercised restraint. But it has in the past also scrambled military aircraft and ships to warn off the American military vessels. Beijing has also warned Washington that potentially close military encounters by the aerial and naval forces of the two sides in the region could trigger a larger crisis.

Washington and Beijing have also traded barbs over the construction of artificial islands and reefs by China in the area and the building of military installations on them. China says the construction is necessary for defense.

The two countries are also locked in a trade war, negotiating a deal ahead of a US-imposed March 1 deadline when American duties on 200 billion dollars worth of Chinese imports may increase from 10 percent to 25.